China Telecom chairman Chang Xiaobing has resigned following his arrest as part of a state crackdown on corruption.

Chang has been detained and questioned as part of an ongoing investigation ordered by President Xi Jinping in 2012. The official’s arrest was announced by the ruling Communist Party's Central Commission for Discipline Inspection, which stated that Chang was under suspicion of “severe disciplinary violations” – a phrase typically used to indicate corruption allegations.

Previously the chairman and CEO of fellow state-owned operator China Unicom, Chang became chairman of China Telecom in August 2015. His duties as chairman will be assumed by the operator’s CEO Yang Jie until a permanent successor is appointed.

The investigation has escalated since its inception, with officials in China’s 2 biggest cities – Beijing and Shanghai – being arrested for the first time towards the end of 2015. President Xi has heralded the crackdown’s successes, noting that it has proven popular among with the public, and has claimed that it will cement the party’s credibility. He has denied any underlying political motivation behind the arrests.

Thus far, the probe has implicated or formally accused over 70 top Chinese officials. Among those convicted are public security specialist Zhou Yongkang and the former chairman of China National Petroleum Corp Jiang Jiemin. Executives from market leader China Mobile are also under investigation.